The program will examine (a) the dependency of moment-to-moment changes in a subject's ideational stream on the joint effects of his incentive commitments and of cues related to them, (b) the dependency of his affective state (including especially depression and apathy) and mental content on the variety, value, and attainability of incentives, and (c) the dependency of spontaneous problem-solving thought, coping behavioral disturbances, alterations of his life situation, and use of drugs (especially alcohol) on the incentive features of his life situation and on the forms and content of his thought. The investigators will track each subject over nine months with a method for sampling his/her stream of reportable ideation (thought sampling), interviews, and questionnaires administered repeatedly. The motivational and life-situational variables are "real-life" subject variables but the form, content, and responsiveness of each subject's mentation are also studied in the laboratory through controlled presentation of stimuli and concurrent monitoring of mental content. The study will focus successively on college students, noncollege adults, and subjects who have episodic experiences with depression or heavy use of alcohol.